Water, water everywhere

We live near a town called Aberystwyth… it’s hit national headlines because it’s been rather wet there. After two days of unusually heavy rain the River Rheidol burst its banks, as did many other streams and rivers in north Ceredigion (we live in the south of the county). The rain on Friday was astonishing, and in combination with a high tide on Saturday, many business and homes were flooded and roads closed. I have friends who have been flooded despite living three miles up in the mountains – the water just came over the land as well as along the stream which they are well above in their house. So when you hear people say ‘what do you expect if you live on a floodplain’ then please remember that not everyone affected lives at sea level or very close to a river.

We have lived in the area for 25 years and have never seen anything like this; but then, there are reports suggesting that there may have been 10 inches of rain in 24 hours up in the mountains on Friday! Of course some of the worst affected areas are those at sea level, where there is also a tidal influence. And it is remarkably short-sighted to continue to build on floodplains. First because the risk of flooding is greater there and, second, because these areas have flooded historically, they have wonderfully fertile soil. Surely we should be using this brilliant natural resource to grow things… even if crops get inundated sometimes, people and their homes won’t.

But it’s not just about where we build houses and businesses, the problem with flooding is that it’s really caused by what’s upstream in the river catchment and how quickly water moves through the landscape. If the land is wooded, lots of rain is intercepted on its way down to the ground, so it is slowed in its journey to the surface and may even have the opportunity to evaporate and return to the air. All vegetation intercepts rainfall, but trees with leaves probably do it best because they have a big surface area. Not only that, but trees create deep permeable soils, with their roots penetrating the ground and lots of organic matter from their fallen leaves acting like a sponge. The more wooded the upper catchments of our rivers, the slower the water moves through them and the more buffering there is from flooding. The opposite is equally true – make the ground less permeable and water moves through it quickly, all arriving at the rivers in a very short time and resulting in flooding. So, roads and storm drains and buildings and concrete yards and patios and field drains all contribute to flooding by speeding up the movement of water through the landscape. Grassland is not as good at intercepting water as woodland, and shallow rooted plants are likely to be associated with less permeable soil than deep-rooted ones.

Whilst the latest flood could not have been avoided no matter what the land use in Ceredigion, it could have been reduced if we had more woodlands (especially in the uplands) and a generally more permeable landscape throughout the river catchments. And many of us can do something about this… if you have a garden, you could make sure that the ground is permeable – so no more patios and paved driveways, consider gravel and grasscrete. Build up the organic matter in your garden – this will help to hold water and be an effective defence against both flood and drought. Install water butts, so that you catch as much of that precious commodity as you can when it’s plentiful and prevent it literally going down the drain. And, finally plant trees and shrubs to intercept the water, root deep into the soil to allow water to percolate down and provide shelter from sun and wind which will dry out your garden anyway.

-oOo-

There are some astonishing photos of the floods on Keith Morris’ facebook page and more photos and a fascinating explanation of the weather that caused the flooding here.

3 Comments

Hi Stacey, I hope that your house has not been too badly affected… some of the pictures are really shocking and the devastation that we saw on Saturday was quite unbelievable. At least the community is pulling together.
As for the solutions, I feel that we should all start doing our bit now – wherever we live. The result will not be immediate, but we have to start somewhere and we have to remember that we shouldn’t do nothing because we can’t do something major.

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